Underground storage tanks for the bulk storing of liquids typically hold up to about 50,000 gallons of liquid. The tanks must be sufficiently strong to withstand internal forces exerted by the weight of the liquid as well as normal external ground forces. They must be reliable in that even the smallest of leaks over time can eventually cause substantial damage to the environment.
Storage tanks which are intended for burial underground to hold gasoline such as commonly found at retail gasoline service stations are typically warranted for at least ten years. The tanks, per se, are expensive as is their installation. Any storage tank which is suspected of leaking can be inspected. Various leak-testers have been developed and commercialized for this purpose. It is also possible to empty the tank and then access its interior for a close-up visual and/or hand-held instrument wall inspection. In the past, any tank with a suspected or actual leakage problem could be repaired. It was conventional to apply a coating of polyester or epoxy coating material to the entire interior of the tank. A coating of from 100 to 300 mils was considered adequate to refurbish the tank to its original integrity.
In certain instances a tank may be too extensively corroded or cracked to repair it. Additionally, recent federal and state regulations in the industry have severely limited the availability of coating a tank's interior as an option to solving a leakage problem. Removing a buried underground storage tank and replacing it with a new storage tank is very expensive. The down-time of the service station is also costly in terms of lost revenue.
In accord with a need, there has been developed a new method of building underground storage tanks. The method utilizes an existing buried tank which is in need of refurbishing. Normal removal and installation costs are eliminated. The resultant in situ formed tank enjoys all of the benefits of factory manufactured tanks.